“Right now, iPad streaming is not having an impact on ratings,” Nielsen VP Matt O’Grady said. “But we’re taking [the project] dead seriously because our clients need to know what the viewing is on tablet and smartphone platforms.”

Time Warner and Cablevision’s participation is significant in part because programming giant Viacom sued both companies over their streaming iPad apps. Cablevision has since settled, while Viacom and Time Warner are still negotiating.

In addition to disputes over compensation and terms of service agreements, Viacom complained that companies like Nielsen couldn’t get good data for tablet streaming. If viewers of The Daily Show or MTV reality shows device-shifted to iPad in large numbers, that could hurt TV ratings or under-count the total audience. Either way, it could could take advertising money off the table.

For media observers, time-shifting, place-shifting and device-shifting of television content is part of the ongoing evolution of our engagement with the digital environment. For cable and content companies, the shift is an important bargaining chip to determine revenue gained and shared. For them to know precisely what that chip is worth, they have to measure how and what viewers are watching.

Negotiations between content companies and cable operators over digital streaming have become increasingly acrimonious. This week, as promised, Fox pulled next-day streaming of its content from Fox.com and Hulu for everyone except Dish TV and Hulu Plus subscribers.

In July, Nielsen VP Jon Gibs said that Nielsen’s initial data suggested that worries about losing TV viewers to streaming video were misplaced. Content companies like Fox or Viacom have much less to fear from Hulu or cable-company apps than illegal downloads of